CHAPTER 7: Electrostatic Fields in Biophysical Chemistry
Published:05 Mar 2021
S. Sowlati-Hashjin, M. Karttunen, and C. F. Matta, in Effects of Electric Fields on Structure and Reactivity: New Horizons in Chemistry, ed. S. Shaik and T. Stuyver, The Royal Society of Chemistry, 2021, pp. 225-262.
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Typical household appliances produce electric fields of roughly 10−10–10−8 V Å−1 and those from cooler climates who use electric blankets to keep warm are exposed to fields of about 10−7 V Å−1. Given these strengths of everyday exposures, it may be surprising that the molecules and organelles of life, such of enzymes and mitochondria, operate in environments that have static electric fields in the range 10−2–10−1 V Å−1. Moreover, those fields are vital for various chemical reactions and processes. Such high fields within our own bodies are possible due to strong localization, while various cancellation effects attenuate or completely nullify their manifestation(s) at a macroscopic level. From the point of view of applications, being able to control localized strong fields would allow for an unprecedented accurate promotion or/and inhibition of various chemical processes. These strong microscopic (static) electric fields are the focus of this chapter. One of the central concepts is the Stark effect, the splitting of spectral lines upon application of (strong) electric fields. This will be discussed by adopting a ground-up approach, that is, starting with the effects of imposed fields on the chemical bonds in simple diatomic molecules which are exploited to interrogate local electric field in large enzymatic active sites, building up to the effects of imposed fields on complex systems including enzyme catalysis and double proton transfers in systems such as nucleic acid base pairs. We conclude with some possible future research directions.